Canon EOS 40D review:
Canon EOS 40D

Though the 40D isn't missing any feature in particular--though I could make a case for mechanical image stabilization--one feature I'd really like to see trickle down from the 1D series, and which I think makes a lot of sense in a camera of this class, is the ability to define acceptable ranges for aperture, shutter speed, and ISO sensitivity when shooting in one of the exposure-priority modes.

As for performance, the 40D is reasonably speedy for its class, and roughly 20 percent faster overall than the 30D. But it still can't keep up with the faster D80. From a cold start to first shot takes only 0.3 second, and under optimal conditions it can focus and shoot in only 0.4 second. A healthy buffer and fast card writes allows the 40D to maintain that pace from shot to shot for both JPEG and raw. Flash recycle time adds slightly less than 0.2 second to that. The 40D has slow- and high-speed burst modes which test out at 3.1 frames per second (fps) and 6.3fps, respectively; the slower mode is for preventing buffer lockups when using a slow CF card. I also found the slower mode a useful speed option when shooting with the Speedlite 580EX flash with sluggishly recycling alkaline batteries. Note that in the case of the 40D a "slow" CF card does not mean "anything slower than UDMA." It doesn't support UDMA, and seems to have sufficient buffer to maintain maximum throughput even with a last-generation SanDisk Extreme III (133x) card.

However, the camera does hit one sour performance note: leisurely low-contrast focusing, which ratchets up low-light lag to 1.2 seconds. This is despite Canon's claim of a 30 percent increase in AF calculation speed. Though not uncommon for a dSLR, we really expect better, especially for this price class. Canon rates the battery, the same 1,390mAH BP-511A used by the 30D, at 1,100 shots (sans flash). Though this is reasonably long, Canon lags behind many of the other manufacturers for providing intelligent power display and estimates of power remaining. The large, bright LCD is easy to view, but like even the best camera LCDs, it renders relatively poor representations of color and exposure.

Photos show excellent dynamic range, with no visible clipping in the highlights or shadows (of correct exposures). Though they definitely fall within an acceptable range, automatic white balance under artificial lights tends to be a bit warm, and even manual white-balance shots measure a tad green-heavy. Automatically balanced sunlit shots render a bit cool. With the exception of certain types of spot-metering cases that I discuss in the slide show, all of the metering schemes delivered excellent, balanced exposures. The 40D's ISO sensitivity caps out at ISO 3,200 and remains visually unobtrusive as high as ISO 800. Beyond that, you can spot noise, but it doesn't jump out of the shadows and knock you over the head.

For Canon devotees, the EOS 40D is a great camera and remains an excellent choice compared with most of the dSLRs in and around its price class--with one exception. Despite its many attractions, the Canon EOS 40D doesn't clearly outshine its closest competitor, the Nikon D90. Though the 40D has the obvious advantage for action shooting--almost double the burst rate and a higher top shutter speed--the D90 generally feels a bit faster and more responsive for single-shot photography, and offers video capture (though flawed) and a higher resolution. I think the 40D ultimately does deliver better photo quality, but some people might find the differences more subtle. And, of course, the more expensive Canon EOS 50D remains a wild card until we've tested it. So for the moment, the 40D gets a hearty, if not wholly unqualified, endorsement.